Intermec PEN*KEY 6100, Руководство программиста

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SECTION 7 Reference, System Information
7-2 PEN*KEY
R
6100 Computer Programmer’s Reference Guide
ROM DOS 5
The ROM DOS 5 product shipped in PEN*KEY 6100 flash memory is produced
by Microsoft Corporation. It provides a number of configuration options that you
can selectively choose when designing a DOSĆbased system. The primary differĆ
ence between ROM DOS 5 and MSĆDOS 5 is that much of the ROM DOS code
executes from the upper memory address space, using readĆonly memory. There
are several ways in which to load the code. In the 6100 Computer, the code is
copied from flash into writeĆprotected system memory, which is referred to as
shadow RAM .
Since DOS is not loaded from disk, the IO.SYS and MSDOS.SYS files required
for booting from a disk are not required in a ROM DOSĆbased computer. The inĆ
itialization code normally loaded from disk is loaded from flash memory instead.
CONFIG.SYS is the first file read from a disk during the ROM DOS boot process.
Unless the CONFIG.SYS file contains a SHELL statement, this default shell
statement is used:
SHELL=D:\COMMAND.COM /P D:\
All the CONFIG.SYS statements that MSĆDOS 5 supports are supported in
ROM DOS 5. This includes the
DOS=HIGH
and
DOS=UMB
statements provided by
MS DOS 5 to load data and DOS programs into the corresponding memory
areas. For
DOS=HIGH
to be useful, an XMS driver, such as HIMEM.SYS, must
be loaded. To use
DOS=UMB
, an XMS manager that supports the upper memory
functions must be loaded. A simple XMS driver named ELANUMP.SYS is availĆ
able for using shadow RAM as upper memory.
ELANUMP.SYS is much smaller and simpler than EMM386.EXE. Using
shadow RAM instead of XMS memory to provide upper memory, it provides more
overall memory to DOS and Windows applications. However, since
ELANUMP.SYS cannot support expanded memory, EMM386.EXE is still the
only method for providing expanded (EMS) memory.
The standard MSĆDOS 5 version of COMMAND.COM is provided in flash. HowĆ
ever, one change has been made to COMMAND.COM to make it more useful on
the 6100 Computer, as described later in this section. If you prefer to use the unĆ
modified version of COMMAND.COM, you can get it from the Tool Kit. Use a
SHELL statement in CONFIG.SYS to override the default shell statement:
SHELL=A:\COMMAND.COM A:\ /P
The CONFIG.SYS file is processed before a command processor is selected. This
particular CONFIG.SYS does not put any unique restrictions on file content.
All the messages displayed by COMMAND.COM have been shortened or split
into multiple lines so that they fit the 20Ćcolumn screen on the 6100 Computer.
"
Error messages are displayed as numbers.
"
The critical error handler displays a menu that includes numeric responses
so that the user can respond without using an alpha keyboard. For examĆ
ple, Abort, Retry, Fail?" becomes: 2) Abort,
1) Retry,
3) Fail?
These numbers are not always in a natural order because each line is disĆ
played independently, pending on the options available. If the numbers
were rearranged to look correct oneway, they would look wrong for another.
"
The Echo command is modified to allow ECHO," to display a blank line
instead of Cannot load program." In a related change, comma (,), equals
(=), and quote () now terminates a keyword comparison.
"
A bug with the GOTO is eliminated so that it works correctly with labels of
two or more characters.
7. Reference,
System Information